An IP Multimedia Subsystem (IMS) is a subsystem in an existing Packet Switched (PS) domain on a Wideband Code Division Multiple Access (WCDMA) network added in the 3rd Generation Partnership Project (3GPP) R5 standard. The IMS uses a PS domain as a bearer channel for upper-layer control signaling and media delivery, introduces the Session Initiation Protocol (SIP) as a service control protocol, and provides plentiful multimedia services by using the features of SIP, such as simplicity, extensibility, and convenient media combination and by separating service control from bearer control. The international standardization organizations that participate in IMS standardization include the 3GPP and the Telecommunications and Internet converged Services and Protocol for Advanced Networking (TISPAN). The 3GPP researches the IMS from the perspective of mobile access. The TISPAN raises requirements for the IMS from the perspective of fixed access and then the IMS is perfected by the 3GPP. Finally, unified control is implemented for fixed access and mobile access over the IMS.
IMS based IPTV provides IPTV services in the entire IMS architecture proposed by the TISPAN so as to fully use the existing mechanisms such as registration, authentication, routing, session control and setup, service triggering, charging, and end-to-end Quality of Service (QoS) to provide streaming services and multimedia services that integrate streaming services and real-time session services for users. That is, a multimedia session from users to contents is completed by an existing session control mechanism of the IMS. During session setup, bearer resources need to be reserved for transmission of media streams.
In the prior art, main features of session setup in a Content on Demand (CoD) service process are as follows: In the CoD service process, users may perform VCR control, such as forward, rewind, and pause for watched contents; therefore, a media control channel used for VCR operations and a media delivery channel used for transmitting watched contents need to be established for the service. According to different modes of establishing a media control channel and a media delivery channel, the CoD service process defined by the TISPAN includes two modes. In the first mode, a media control channel and a media delivery channel are established during SIP session setup at the same time. In the second mode, a media control channel is established during initial session setup, and then a media delivery channel is established through a session change.
The prerequisite to the use of the first mode is that a User Equipment (UE) has obtained media information of watched contents from an Electronic Program Guide (EPG), such as the media lines, for example, audio, video, and text media lines, of the contents. Therefore, the media delivery channel may be negotiated and established. If the second mode is adopted, a media control channel (generally an RTSP channel) is negotiated and established through a SIP session setup process; a media exchange control session is set up between a UE and a Media Function (MF); the network parameter information of media is obtained by exchanging media control messages; and then a content delivery channel is established during a session change.
In fact, compared with the first mode, the second mode has the following defect: Session setup takes a long time. The general process is as follows: After a session is set up initially (by using a SIP message), the UE and the network (MF) initiate a media control message (generally an RTSP DESCRIBE message) to set up a media control session, and exchange media contents in a media control session message, and finally, a media channel is established through a session change process (by using a SIP message). As a result, user service experience is poor. Therefore, the restriction on the application of the second mode in current specifications is as follows: establishing a content delivery channel during an initial session, namely, the second mode, is optional only when a network provides only network parameter information of a media control channel rather than the network parameter information of a content delivery channel for users.
During the implementation of the present disclosure, the inventor discovers at least the following problems in the prior art:
If the second mode is adopted, more interactions are required between the UE and the network; more requirements are raised for the UE; session setup is delayed; and user experience becomes poor.